Clinical studies have generally shown that phosphomonoesters, phosphodiesters, and choline containing compounds are elevated in tumors compared to normal tissue. Preclinical work suggests that malignant breast tumors have elevated phosphocholine compared to normal tissue. We studied twenty female patients, age 25-68. Three patients were excluded for technical reasons (eg, motion). We examined 10 carcinomas ranging in size from 1-5 cm; the remaining patients presented with fibrocystic changes (2), fibroadenoma (2), tubular adenoma (1), and other benign processes (2). The Cho resonance at 3.2 ppm was clearly present in spectra from 6 of the 10 CAs and statistically resolved in another. In contrast, only one rare benign lesion, the tubular adenoma, showed Cho. 1H MRS can provide sufficient sensitivity and spectral resolution at 1.5 T to observe choline in breast lesions. This is facilitated by using closely coupled multicoils that compress the breast. The administration of Gd-DTPA does not appear to contraindicate performing these studies. Quantitation of choline is complicated by overlapping signals from water and fat, however preliminary clinical 1H MRS studies done at 4.0 T have not revealed choline in benign breast lesions or normal breast tissue despite the increased chemical shift dispersion and SNR available at the higher field. These results suggest the choline resonance may be useful to characterize small breast lesions at 1.5 T, either alone or in combination with MR imaging criteria. Furthermore, the combination of MR imaging and 1H MRS may improve the diagnostic performance of MR imaging criteria alone, particularly when high specificity is clinically important.